The most common implement for dental hygiene is the toothbrush. The mechanical action of the toothbrush bristles aids in the removal of food particles, plaque, and the like. The toothbrush is normally used with a toothpaste. Prior to about 1955, a typical toothpaste consisted of a surfactant and an abrasive material. These products were simply intended to augment the mechanical action of the brushing.
In 1955, CREST.RTM. toothpaste with fluoride, a Trademark of The Procter & Gamble Company of Cincinnati, Ohio, was introduced and the toothbrush and fluoride toothpaste combination proved to be a suitable means to deliver a fluoride treatment to the teeth surfaces. Subsequently, other active ingredients, such as tartar control agents, have been added to toothpaste to provide further dental hygiene benefits. Consumers have also turned their attention to the cosmetic aspects of dental care, such as teeth straightening and whitening.
Given the success of delivering chemicals which provide therapeutic benefits for oral care, it is reasonable to expect similar success in accomplishing the cosmetic benefit via routine brushing. For example, products have been introduced which claim to whiten teeth. However, in spite of the claims, the combination of the low allowable strength of the orally used chemicals and the significant contact time necessary for whitening to occur effectively prevents significant whitening via a regular program of brushing. As a consequence, people who are serious about whitening their teeth and who have been disappointed by the results of whitening dentifrices, often resort to professional help for whitening their teeth.
Professional teeth whitening programs provided by dentists generally fall into two categories: an in-office bleaching procedure and an outside-the-office bleaching procedure. The in-office procedure involves several visits, each of which begins with the fabrication of a specially fitted rubber dam within the mouth to prevent the bleaching chemicals, typically hydrogen peroxide, from contacting the soft oral tissue. The production of the rubber dam within the patient's mouth may be both painful and time consuming. However, the strength of the peroxide bleach mandates the use of the dam. The in-office procedure may also leave the teeth sensitive to heat and cold and is very expensive.
The outside-the-office bleaching program differs in that the patient applies the bleaching agent to his or her own teeth using a lower strength chemical over an extended period of time, typically several hours a day for several weeks. The outside-the-office program typically requires an initial fitting in the dentist's office for an appliance which is specific to the particular patient. The appliance is a device that is fabricated to fit precisely onto the patient's teeth and is used to deliver to the patient's teeth a bleaching product, such as a gel containing urea/hydrogen peroxide complex. The patient is responsible for measuring and applying the bleaching agent to the surfaces of the teeth using the appliance as the means for delivery and containment.
Because the appliance is reused, it must be sufficiently robust to endure repeat handling, cleaning, filing, installation, and wearing. Such appliances are relatively rigid in order to maintain fit during repeat use. As a result, the edge of an appliance is generally stiff, often causing gum irritation; and its substantial thickness is usually apparent to both the wearer and others. Typically, a patient uses the device in time periods when social contact can be avoided.
There are now non-professional programs available to persons interested in whitening their teeth using commercial products available at drug stores. The commercial products provide a kit which includes a generic appliance and a container of bleaching gel. The obvious appeal is the lower cost of the program. A major disadvantage of this "one size fits all" appliance is the greater void between the interior walls of the appliance and the teeth versus the professionally fitted appliance. Hence, in order to insure intimate contact of the bleaching gel and the teeth surfaces, more bleaching gel is required. Furthermore, the poorer fit means a greater loss of bleaching gel onto the gums, into the oral cavity, and eventually ingested. The commercial kits, like the outside-the-office professionally administered program, require the user to clean and to reuse the appliance. Since generic appliances are not fitted to the individual user, they are even more bulky in the mouth than the fitted appliances and thus they restrict social discourse to a greater degree.
One attempt to remedy some of the problems of the commercial kits is disclosed in U.S. Pat. No. 5,575,654, issued to Fontenot on Nov. 19, 1996. Fontenot discloses a prepackaged moldable dental appliance, adapted to fit a wide range of variously sized dental arches, which contains a premeasured amount of medicinal or bleaching agent. In use, the dental appliance is removed from the packaging, aligned in a parallel fashion to the edges of the teeth and pushed over the teeth in the direction of the periodontal tissue until it covers the teeth surfaces. The primary benefit of the device disclosed by Fontenot is elimination of the measuring and filling of the appliance and the disposability after each use. However, it has been observed that the device frequently has the problems of bulk and compromised fit.
A second solution is disclosed in U.S. Pat. No. 5,310,563, issued to Curtis et al. on May 10, 1994. Curtis et al. disclose a putty-like material which is formed by pressing against the teeth. It is held in place by mechanical engagement with undercut surfaces and by friction. The composition encapsulates the active. The active migrates from the composition to the gums and tooth surfaces rather than being directly in contact with them. Presumably, the required wearing time is increased, which may be a significant negative.
What is needed is a low cost commercial delivery system, which has a customized fit for a minimal volume of a tooth whitening substance, and which is in conformable contact with the appropriate tooth surfaces for rapid delivery of an active in such substance. In addition a delivery system is needed which does not require extensive user placement manipulation to be certain of good contact. Furthermore, what is needed is a non-bulky active containment means that will permit the wearer to use the system during social discourse without interfering with the wearer's speech or appearance. Also needed is a containment means that will protect the tooth whitening substance from erosion from contact with inner mouth surfaces.